A caster having a wheel pivotally supported upon arms wherein the arms are elastomerically biased to absorb shock and improve the caster rolling characteristics.
Heavy-duty casters are used to support relatively heavy loads transported by small lift trucks, material handling carts, and the like. By using biasing means to transmit the supported weight between the caster wheel and the caster body, the load bearing ability of the caster is improved resulting in smoother operation, ease of movement of the caster supported truck or vehicle, and improved truck travel operation due to caster wheel wear.
Steel compression springs have been used to bias resiliently supported casters, but such springs as are necessary to achieve the desired resilient supported characteristics are relatively large and not readily adaptable to many caster installations wherein the overall vertical dimension available for the caster is limited, and the vertical profile of the caster assembly must be concise.
Heretofore, it has not been possible to provide a low profile caster wherein the wheel is resiliently supported, the cost is relatively inexpensive, and the vertical caster dimension is relatively concise.
It is an object of the invention to provide a heavy-duty resiliently supported caster wherein the resilient caster characteristics are achieved through a torque transmitting polyurethane material wherein high loads may be elastomerically absorbed.
Another object of the invention is to provide a heavy-duty resiliently supported caster which is of a low vertical profile and may be installed in low profile environments without sacrifice of the elastomeric and shock absorbing weight characteristics of the caster.
The caster in accord with the invention includes a support plate affixed to the truck, forklift, or other structure to be supported by the caster. The caster body is mounted to the support plate either in a fixed relationship, or in a rotative relationship by the use of ball bearings if the caster is to be of the xe2x80x9cpivotedxe2x80x9d type. Such caster choices are well known.
The caster wheel is rotatably supported between a pair of pivoted caster arms mounted to the caster body. The upper end of the caster arms are attached to an insert which is part of the core of an elastomeric assembly wherein an elastic material, such as polyurethane, is bonded to an internal core, and is exteriorly bonded to a tubular housing, wherein a rotative relationship between the elastomeric material and the housing and the core is prevented.
The housing, which is of a non-circular transverse cross section, as is the core, is attached to the caster body intermediate the caster arms. The caster arms are attached to the ends of the core insert by a non-circular torque transmitting configuration, and held in this relationship by bolts threaded into the core ends. Stop projections are defined on the caster arms for engaging the caster body with excessive deformation of the elastomeric material takes place during operation.
The weight carried by the caster is transmitted through the elastomeric material in a torque transmitting manner, and in this way, the caster wheel is elastomerically related to the caster body to achieve the desired biased caster operation. As the ends of the elastic material are protected by the upper ends of the caster arms, the likelihood of damage to the elastomeric material is minimized, and the arrangement of components, as will be appreciated from the attached drawings, permits the entire caster assembly to be of a concise configuration and installable in applications wherein a low vertical profile is required.
In an embodiment of the invention, stop arms are bolted to the core insert in a non-rotative relationship and these stop arms will bear against the caster body if excessive elastomer deformation occurs. The upper ends of the stop arms include a torque coupling receivable within a slot defined in the upper end of the caster arms and a toothed washer mounted upon the insert bolts cooperating with teeth defined in the outer surface of the caster arms permits the caster arms to be adjustably positioned relative to the caster body and support. In this manner, the vertical height of the caster can be easily adjusted to accommodate the caster to a particular installation without requiring major modification.